This invention relates generally to controlling relative motion of a tool and workpiece. In particular this invention relates to controlling oscillation of a tool carried by a manipulator to produce a predetermined oscillatory pattern relative to a workpiece feature.
In general, operations for joining workpieces by welding or glueing require that the workpiece joining material be distributed across the seam or joint formed by the workpieces. Special purpose devices are known for providing oscillation of a tool tip, for example, a welding torch, through a pattern defined relative to the seam as welding progresses along the seam. Such devices may be stationary while the workpiece is moved or may move while the workpiece is stationary. Typically these devices are designed for particular applications and are not suited to doing work on both flat and cylindrical workpieces. As an improvement over these special purpose devices, program controlled manipulators are suitable for a greater variety of workpiece joining operations including both cylindrical and flat workpieces. Methods and apparatus for effecting oscillatory motion of a tool tip carried by a manipulator as it advances along a programmed path are known. However, these methods are not applicable where the workpiece is rotated to effect relative motion between the tool tip and the seam.